Examples of post-mortality alteration in Recent brachiopod shells and (paleo)ecological consequences

摘要: Post-mortality alteration of brachiopod shells under normal environmental conditions leads to high taphonomic loss, and a poor contribution the biodetrital soft sediment. The successive stages which undergo are: (bio)degradation organic matrix → shell softening structural disaggregation or/and mechanical fragmentation; these processes depend on structure (number layers) composition (organic inorganic components), but very little conditions, except for dissolution constituents. Among Brachiopoda, three types occur different — Type I: two-layered chitino-phosphatic (species ofLingula andGlottidia) displays rapid degradation abrasion, leading total disappearance in 2 3 wk; II: carbonate shell, e.g.Terebratulina spp. [but notNotosaria nigricans (Sowerby) may constitute fourth type], exhibits secondary layer, softening, disintegration 6 7 mo with concomitant calcitic microfibres sediment; III: three-layered e.g.Gryphus vitreus (Born), undergoes fragmentation anterior two-thirds slow (because thick tertiary layer) posterior portion components (mainly make relatively minor